INTRACELLULAR PROTEINASES OF GROWING AND DIFFERENTIATED HAPLOID CELLS OF PHYSARUM-FLAVICOMUM

The profiles of intracellular proteinases in growing myxamoebae-swarm cells and dormant microcysts of Physarum flavicomum Berk. were determined. Extracts were subjected to column isoelectric focusing and the fractions assayed for pH and ability to hydrolyze Azocoll. About 18 enzymes were detected in the growing cells with the greatest activity occurring at isoelectric points (pI) 9.0, 9.2, 9.5, 5.5, 3.3, and 9.8 in decreasing order. However, there was a shift in activity toward enzymes with a more acidic pI in the microcysts; of the 15 enzymes detected, the order of decreasing activity was pI 5.3, 8.3, 4.5, 3.5, 3.9, and 4.2. Extracts were also focused in gels and enzyme fractions subjected to discontinuous gel electrophoresis followed by leucine aminopeptidase (LAP) assays using l-leucyl-4-methoxy-β-naphthylamide as substrate. LAPs were detected in amoebal extracts with pI's of 5.5, 5.0, and 4.3, while cyst extracts contained LAPs at pI's 5.3, 4.5, and 3.9. © 1979 Academic Press, Inc. All rights reserved.